As the title character of Judge Dredd, a heavy-metal law enforcer who roams the sets of Blade Runner — excuse me, the futuristic urban wasteland of Mega-City One — arresting, ”judging,” and (mostly) offing criminal scum, Sylvester Stallone wears a suit of paramilitary robot armor that’s so huge and bulky and dehumanizing it makes Val Kilmer’s S &amp M Batsuit look like something off the Gr’Animals rack. In the early scenes, the getup is completed by a helmet that covers most of Stallone’s face, leaving only his mouth and jaw exposed. All you can see are those thin, sneering parrot’s lips, and the effect is a little disconcerting, since it emphasizes the slurry, drugged-sounding lassitude of Stallone’s vocal delivery. (Fortunately, he doesn’t wear the helmet for long.) The hulking, stud-android armor doesn’t just protect Judge Dredd from criminal bullets. It protects Stallone as well, saving him from our expectation that he’s going to have to do anything other than scowl, pull the trigger, and grunt out campy-sadistic tag lines like ”Court’s adjourned!” And the movie shields him too. It’s as imposingly overscaled as that bodysuit — a big, dumb, gaudy, amusingly disreputable action fantasy that barely bothers to shrug at the fact that its hero is, in essence, a 21st-century storm trooper, the kind of guy who shoots first and checks for innocent bystanders later.

Judge Dredd is based on a popular British comic strip, but that doesn’t mean it isn’t a rip-off of your favorite sci-fi blockbusters. By now, even the most ”artful” comics are essentially recombinant versions of Hollywood’s most nihilistic action fantasies. (The vengeful bravado that makes for cheap thrills on screen can look to adolescents — and to overgrown adolescents — like philosophical defiance when it issues from a pen-and-ink drawing.) Judge Dredd unfolds in a wearyingly familiar futuristic grungescape: the inevitable amalgam of Blade Runner and The Road Warrior. But the sets, all neon clutter and looming skyscrapers, are genuinely spectacular. One chase sequence features too many obvious matte shots yet still manages to thrill by making Mega-City One look like a vertiginous M.C. Escher dreamworld.

As a character, Judge Dredd is Dirty Harry in RoboCop’s armor, and Stallone plays him in the early Eastwood style, voice lowered to a monotone, eyes glinting with noble rage. (The glint means: I’d really enjoy killing your ass.) The movie pits Dredd against his long-lost criminal brother, Rico (Armand Assante), who frames him for murder and then slaughters the city’s brigade of law-enforcement judges. He intends to replace them with clones of himself, a plan so megalomaniacal it actually succeeds in making you forget that Dredd’s death-squad tactics are just a quieter form of fascist posturing. Dredd, of course, needs a wise-guy buddy, so the movie pairs Stallone with Saturday Night Live’s Rob Schneider, a human mugging machine who flits around our hero like an organ-grinder’s monkey. Judge Dredd is serviceable low-grade entertainment. If I can’t work up much enthusiasm for it, that’s because the sets are so nifty and detailed, and Stallone pumps so many rounds of bullets into each one of them, that the movie, by the end, practically seems intent on destroying itself. C+